The present invention relates to a panel-type display device in which display luminance is controlled through use of an applied voltage. More specifically, the present invention relates to a technology for display devices and display device driver circuits that makes it possible to lower power consumption requirements by controlling the number of colors to be displayed.
An example of a technique that makes it possible to lower power consumption requirements by using an applied voltage to control display luminance is embodied in the display device described in “Asia display/IDW '01 proceedings” (p. 1583–1586, ITE/SID Publications). This display device performs color reduction by dithering incoming gradation data, thus simulating the number of colors in the original gradation data (hereinafter also referred to as the real color count) with a smaller number of colors. As a result, the power consumption of the device is lower than when the real color count is directly displayed.
Color reduction operations, such as dithering, generally allow selection of the degree to which the color count is reduced from the real color count (hereinafter referred to as the color reduction rate). There is less image degradation with smaller color reduction rates (close to the real color count) and more image degradation with larger color reduction rates. On the other hand, a smaller number of colors for display means that the display device circuitry has less to do, thus allowing power consumption to be reduced.
As a result, different implementations are possible depending on the usage of the display device, e.g., high-quality displays with little color reduction and low-power displays with more color reduction. However, the color reduction rates in the conventional technologies have been constant (262,144 colors to 4096 colors). Thus, the usage of this type of technology has not been considered practical.